逻辑分辨率（iOS开发及设计人员使用）：
iPhone 4s/4/3GS/3G: {{0, 0}, {320, 480}} 宽高比 0.666
iPhone 5/5S/5c/SE: {{0, 0}, {320, 568}} 0.5633
iPhone 6: {{0, 0}, {375, 667}} 0.5622
iPhone 6Plus: {{0, 0}, {414, 736}} 0.5625
iPhone 6s: {{0, 0}, {375, 667}}
iPhone 6s Plus: {{0, 0}, {414, 736}}
iPhone 7: {{0, 0}, {375, 667}}
iPhone 7Plus: {{0, 0}, {414, 736}}
iPhone 8: {{0, 0}, {375, 667}}
iPhone 8Plus: {{0, 0}, {414, 736}}
iPhone X: {{0, 0}, {375, 812}} 0.4618